Effect of Physical Processing of Commercial De-oiled Rice Bran on Particle Size Distribution, and Content of Chemical and Bio-functional Components

Rice bran is a rich source of nutrients and
nutraceuticals, which has bio-functional properties. Deoiled
rice bran, a major byproduct of rice bran oil industry,
is not yet efficiently utilized for human consumption due to
its poor edible quality. Various physical processing methods
like sieving, pin milling and air classification were applied
to upgrade the quality of bran and also to investigate its
effect on particle size distribution, content of ash, protein,
total dietary fiber, insoluble fiber, soluble fiber and
oryzanol as well as total antioxidant activity in bran
fractions. Sieve separation resulted in an increase in the
content of protein and bio-functional components like
soluble fiber and oryzanol as well as total antioxidant
activity. Pin milling and sieving resulted in smaller particle
size fraction without loss in the content of protein and other
bio-functional components and antioxidant activity. Air
classification of this material resulted in significant decrease
in ash content with moderate increase in protein
content and significant increase in the contents of oryzanol
and soluble fiber and the total antioxidant activity. This
resulted in quality improvement of commercial de-oiled
bran viz., reduction in coarse bran fraction (>250μm size
particles) from 65% to 0%, content of ash from14.3 to 13.1 g/
100 g, and insoluble fiber from 49.3 to 46.1 g/100 g, and
increase in the content of protein from 13.7 to 17 g/100 g,
soluble fiber from 2.75 to 4.35 g/100 g, oryzanol from 13.6
to 18.1 mg/100 g, and total antioxidant activity from 61 to
96 mM α-tocopherol equivalent/g. About 30% edible and nutrient rich rice bran, which can be used as an ingredient in the
bakery products and health food formulations, was obtained
from unutilized commercial de-oiled bran by this process